Characterization of an Expanded IL-10-Producing-Suppressive T Cell Population Associated with Immune Tolerance

An increase in the number of glucocorticoid-induced tumor necrosis factor receptor-family related gene/protein (GITR)⁺CD25^- (or fork-head box protein 3: Foxp3^-) CD4⁺ T cells, after treating a mouse model of arthritis with fingolimod (FTY720), and a pathogenic antigen may play a key role in the establishment of immune tolerance. In this study, we characterized a specific expanded T cell subset in this population. Mice with glucose-6-phosphate isomerase peptide (GPI_325-339)-induced arthritis were treated with FTY720 (1 mg/kg, per os) and GPI_325-339 (10 µg/mouse, intravenously) for five days, starting from the onset of symptoms. The expanded GITR⁺CD25^- (or Foxp3^-) CD4⁺ T cell population and its cytokine production were examined using flow cytometry. Furthermore, time-dependent changes in T-bet and/or early growth response gene 2 (Egr-2) expression in this T cell subset were examined. The density of T cell immunoreceptors with immunoglobulin (Ig) and immunoreceptor tyrosine-based inhibition motif domains (TIGIT)⁺CD39⁺ cell subset in the GITR⁺Foxp3^-CD4⁺ T cell population was significantly increased only in the combined treatment group, compared to that in the untreated and single-treatment groups. In the TIGIT⁺CD39⁺GITR⁺Foxp3^-CD4⁺ T cell population, T-bet⁺Egr-2⁺/T-bet⁺Egr-2^- cell ratio increased in the latter stage of the treatment. Furthermore, this T cell subset, which corresponded to a T helper 1 (Th1) response, produced high levels of both interleukin (IL)-10 and interferon (IFN)-γ. In conclusion, expanded TIGIT⁺CD39⁺GITR⁺Foxp3^-CD4⁺ T cells shifted from an effector Th1 to IL-10-producing-suppressor T cell phenotype, which may promote an immune-tolerant state.

[Management under anesthesia of a patient with renal cell carcinoma extending into the retrohepatic inferior vena cava with the aid of partial cardiopulmonary bypass]

A 70-year-old male with renal cell carcinoma extending into the retrohepatic inferior vena cava was scheduled for radical nephrectomy with vena caval resection under general anesthesia. He had received partial gastrectomy for gastric cancer twelve years before. Computed tomography and inferior vena cavography confirmed that the vena cava was almost completely occluded and that a collateral venous network was well established. It was considered that the surgical approach to the retrohepatic cavals area was technically very difficult, and that there was a high possibility of a pulmonary embolus during the surgical manipulation. To prevent a pulmonary embolus and get good control of the vena cava above the tumor and below the hepatic vein, we decided to use a partial cardiopulmonary bypass (CPB) until the vena cava was clamping above the tumor. Anesthesia was induced with propofol and fentanyl, and maintained with fentanyl and isoflurane-N2O-O2. In the partial CPB blood from the hepatic vein was drained from the inferior vena cava cannula through right atrium, oxygenated by microporus membrane oxygenator, and returned to the left femoral artery. Cannulation to drain the venous circulation entering the vena cava below the tumor was abandoned because the extensive collateral venous network ultimately drains into the superior vena cava. The partial CPB time was 90 min, and the bladder temperature during the CPB was 35-36 degrees C. During the 7.3 hr procedure, the pulmonary embolus did not occur and the total blood loss was 5515 ml. The patient made an uncomplicated recovery and was discharged 30 days after the operation. This newly reported partial-CPB method may be safe and effective for the management under anesthesia of other patients.

Recovery of cardiac norepinephrine concentration and tyrosine hydroxylase activity by the central alpha2-adrenoceptor agonist guanabenz in rats with aortic constriction

Depletion of cardiac norepinephrine has been reported in cardiac hypertrophy. This depletion causes less support for cardiac output in response to sympathetic nerve activation. The central nervous system is thought to be involved in this abnormality. Correction of this abnormality is expected to restore proper support for the heart. Clipping of the ascending aorta or a sham operation was performed in 10-week-old rats. At 4 weeks after the operation, the left ventricular norepinephrine concentration in clipped rats decreased (p<0.01). The clipped rats and sham-operated rats were treated with either guanabenz (1 mg/kg) or a vehicle for 4 weeks starting from fifth postoperative week. The level of left ventricular norepinephrine increased more in clipped rats treated with guanabenz (469+/-37 ng/g) than in clipped rats treated with a vehicle (325+/-28 ng/g). The norepinephrine concentration in the left ventricle recovered significantly after the treatment with guanabenz (p<0.001). Tyrosine hydroxylase activity in the left ventricle also recovered after treatment with guanabenz (p<0.01). Modulation of sympathetic nerve tone by the alpha2-adrenoceptor agonist restored cardiac norepinephrine concentration and tyrosine hydroxylase activity. This could be a new approach to the treatment of heart failure.

[Role of cardiac sympathetic nervous activity in exercise--changes in catecholamine level on forced swimming rat]

Endurance exercise demands full adaptive mechanisms in various organs. Sympathetic nervous system is said to play an important role on supporting the cardiac function through norepinephrine (NE) release. The purpose of this study is to investigate the role of cardiac sympathetic nervous system in exercise by measuring the activity of cardiac tyrosine hydroxylase (TH), rate-limiting enzyme in catecholamine (CA) synthesis and concentration of NE and 3,4-Dihydroxyphenylethylene glycol (DHPG), major metabolite of CA.

METHODS

14 week old Wistar rats were forced to swim in 37 degrees C water bath for 90, 150, 240, 330 minutes, respectively. Some of them couldn't swim until the fixed time (group D). After swimming, they were promptly decapitated ++ and then concentration of plasma, cardiac and adrenal CA, activity of cardiac TH and concentration of cardiac DHPG were measured. Myocardial contractility was also measured using removed papillary muscle.

RESULTS

(1) Plasma CA concentration didn't change between control and each swimming group, but elevated in group D. (2) Cardiac CA concentration decreased as swimming was prolonged and markedly reduced in group D. (3) Adrenal CA concentration in swimming group tended to elevate and decreased in group D. (4) There were no differences in activity of cardiac TH between swimming group and control. (5) Concentration of cardiac DHPG were decreased in group D compared with control. (6) There were no differences in myocardial contractility between control and group D. These results suggest; prolonged exercise seemed to be supported by cardiac sympathetic NE release and was no longer continued when the cardiac sympathetic support was reduced.

Cardiac acetylcholine concentration in the mouse

We measured cardiac acetylcholine (ACh) in mice using four different methods. The mice in the in vivo irradiation group received microwave irradiation and then the hearts were removed. The animals in the in vitro irradiation group were decapitated and only the hearts were irradiated. The animals in the non-frozen group were decapitated and ACh was measured soon after the removal of the heart. The animals in the frozen group were decapitated and the hearts were frozen. There were significant differences in ACh concentrations between the in vivo irradiation group and the other groups. We also measured the ACh concentrations in both atria and ventricles after the mice were irradiated while alive. The atrial ACh concentration 1.70 +/- 0.70 nmol/g (mean +/- SD) was significantly higher than the ventricle concentration 1.07 +/- 0.30. We concluded the microwave irradiation of animals was suitable method of sacrifice for the measurement of cardiac ACh.

Direct blood pressure monitoring in patients with pheochromocytoma

In patients with pheochromocytoma, blood pressure was monitored continuously for 2 days using direct measurement techniques. Systolic blood pressure sometimes increased to more than 300 mmHg. These sudden elevations of blood pressure were associated with increased levels of plasma catecholamines. Pre-operative prazosin and propranolol therapy lowered mean systolic and diastolic blood pressure throughout the 2 day observation periods and was associated with decreased hematocrit levels. However, these agents did not prevent the rapid elevation of blood pressure.